# fill the array with 0s (float)
a = [ [ [ 0. for z in range(5)] for y in range(5)] for x in range(5)]

# access by coordinates x, y, z
a[1][2][3] = 1.

for x in range(5):
    for y in range(5):
        for z in range(5):
            print x, y, z, ':', a[x][y][z]
            
